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PCIe rescan in Linux

Question asked by jeffrey coffman on Mar 22, 2013
Latest reply on May 18, 2017 by Jeffrey Coffman



We are developing an FPGA device, which is going to be connected to an i.MX6 as a PCIe endpoint device.  I'd like to configure the FPGA once the system is up and running, and of course at this point the kernel has already probed the PCIe bus and hasn't see anything yet.  I'd like to be able to rescan the PCIe bus once the device is configured and the PCIe core is running.


I've done some searching and seen some reference to doing an echo 1 > /sys/bus/pci/rescan.  This doesn't really have any effect and I am told you need hotplug support for this to work.  So I am wondering the following:


1.  Does 3.0.35 Linux kernel support hotplug for the i.MX6?  I don't see it as option in the menuconfig.

2.  Does my device need to support hotplug, I assume it has to assert PERST#.

3.  My device isn't going to be hot swappable, I just need to delay the Kernels initial probing of the PCIe bus until the FPGA is configured.  Is this possible todo without hotplug, or are pretty much stuck needing the hotplug service?


If someone out there can help explain this in more detail, that would be great.